JP4843200B2 - Process for producing organopolysiloxane materials crosslinkable to elastomers - Google Patents

Description

  The present invention relates to a process for producing an organopolysiloxane material that crosslinks to an elastomer, so-called RTV-1-substance, using a polydiorganosiloxane having a hydroxy group at the end.

  Methods for producing crosslinkable materials upon entry of water at room temperature have been known for a long time. Typically, such materials comprise an organopolysiloxane having substantially at least two hydrolyzable groups, such as alkoxy groups, and a cross-linking agent having at least three hydrolyzable groups, such as alkoxy groups. And a catalyst, such as an organotin compound. In this case, the end-capped siloxane used as the base polymer is produced by so-called “end capping”.

End capping is essential for the production of RTV-1-materials that are crosslinkable under alcohol degradation. End capping can be done in many ways:
1) Direct formulation with OH-terminated organopolysiloxane and titanium catalyst; 1.1) For example, using orthophosphate with chalk as described in German Patent 1,950,416 1.2) in situ use of (alkoxy) Si-N-compounds and combinations of Lewis acids and amine compounds as described in EP 137883. In-situ end-capping of OH-terminated organopolysiloxanes; 1.3) In-situ using trialkoxysilanes and carboxamides or salts thereof as disclosed, for example, in EP-A-304701 End capping at; subsequently, the material is further formulated.
2) Separate production of special polymers terminated.
3) Compounding at elevated temperature with organopolysiloxanes terminated with hydroxy groups and alkoxysilanes (alkoxysiloxanes) and subsequently removed solid catalysts as described, for example, in US Pat. No. 3,383,355 .
German Patent No. 1,950,416 European Patent Application No. 137883 European Patent Application No. 304701 US Pat. No. 3,383,355

  The present invention was challenged to improve end capping during the production of the crosslinkable RTV-1-material described above.

The subject of the present invention is a process for the production of organopolysiloxane materials that are crosslinkable to elastomers, which comprises:
(A) an organopolysiloxane having at least two hydroxyl groups;
(B) Formula RSi (OR ¹ ) ₃ (I),
[Wherein R represents a methyl group or a vinyl group, and R ¹ may be the same or different, and represents a methyl group or an ethyl group] and / or a partially hydrolyzed product thereof, The silane of (I) and / or its partial hydrolyzate is to be used in an amount of at least 0.7 parts by weight with respect to 100 parts by weight of component (A),
(C) An organosilicon compound having at least one group having basic nitrogen bonded to silicon through carbon is mixed with each other at a temperature of 20 to 90 ° C. and a pressure of the ambient atmosphere to be converted into a premix, Characterized by adding tin catalyst (D) when 1-60% of the number of SiOH groups in (A) is still present.

Component (A) is preferably a long-chain organopolysiloxane essentially terminated with a hydroxyl group, particularly preferably the formula HO— [R ² ₂ SiO] _m —H (II)
In this case, R ² may be the same or different, and represents an alkyl group having 1 to 6 carbon atoms, and m represents an organopolysiloxane (A) of 100 to 100 at 25 ° C. It is selected to have a viscosity of 1000000 mPas, in particular 500-250,000 mPas.

Preferably, the group R ² is particularly preferably a methyl group.

  Preferably component (B) is vinyltrimethoxysilane.

  For the production according to the invention of crosslinkable substances, component (B) is preferably used in an amount of at least 1 part by weight, particularly preferably from 1.5 to 8.5 parts by weight, each of component (A). Is done.

  Component (C) is an organosiloxane and organosilane having at least one group with basic nitrogen bonded to silicon via carbon, in this case an aminosilane, for example γ-aminopropyltrimethoxysilane Aminomethyltriethoxysilane and N-aminoethylaminopropyltrimethoxysilane are particularly preferred.

  In the process according to the invention, component (C) is preferably used in an amount of 0.5 to 8.0 parts by weight, particularly preferably 1.5 to 5.5 parts by weight, based on 100 parts by weight of siloxane A. The

  Component (D) is preferably an organotin compound, such as di-n-butyltin diacetate, di-n-butyltin octoate, di-n-butyltin dilaurate or di-n-butyltin oxide and (poly) -) Reaction products with alkoxysilanes, in which case the reaction catalyst is particularly advantageous.

  In the process according to the invention, component (D) is preferably from 0.01 to 3.0 parts by weight, particularly preferably from 0.01 to 1.0 parts by weight, in particular from 100 parts by weight of each crosslinkable substance. In an amount of 0.05 to 0.5 parts by mass.

In the case of the process according to the invention, all fillers that have hitherto been used for the preparation of RTV-1-substances can be used as filler (E). Examples of fillers (E) are non-crosslinkable fillers, ie fillers having a BET surface area of up to 50 m ² / g, such as quartz, diatomaceous earth, calcium silicate, zirconium silicate, zeolite, metal oxide powders, such as oxidation Aluminum, titanium oxide, iron oxide or zinc oxide or mixed oxides thereof, barium sulfate, calcium carbonate, gypsum, silicon nitride, silicon carbide, boron nitride, glass powder and plastic powder such as polyacrylonitrile powder, and reinforcing filling Agents, ie fillers having a BET surface area of more than 50 m ² / g, such as pyrogenic silicic acid, precipitated silicic acid, precipitated chalk, carbon black, such as furnace black and acetylene black and higher surface area silicon-aluminum mixed oxides, As well as fibrous fillers such as asbestos and Plastic fiber. The described fillers may be hydrophobized, for example by treatment with organosilanes or organosiloxanes or treatment with stearic acid or etherification of hydroxyl groups to alkoxy groups.

  When using the filler (E), pyrogenic silicic acid, coated calcium carbonate or uncoated calcium carbonate, metal silicate, quartz or carbon black are preferably important.

  This is advantageous when the filler (E) is used to produce a crosslinkable material according to the invention, in which case it is advantageous for each 100 parts by weight of the crosslinkable material. An amount of 10 to 35 parts by weight, particularly preferably 15 to 30 parts by weight, is important.

  In the case of the process according to the invention, all stabilizers that have heretofore been used for the preparation of RTV-1-substances may be used as stabilizer (F). Examples of stabilizers are phosphorus compounds at all oxidation stages.

  Preferably component (F) is a phosphorous compound, such as phosphoric monoester, phosphoric diester or phosphonic acid, particularly preferably octylphosphonic acid.

  This is advantageous when the stabilizer (F) is used to produce a crosslinkable material according to the invention, but in this case it is preferably 0 for each 100 parts by weight of the crosslinkable material. An amount of 0.05 to 2.0 parts by weight, particularly preferably 0.1 to 0.4 parts by weight, is important.

  Other substances (G) which are optionally used are in particular 50 to 1000 mPa.s. plasticizers with viscosities in the range of s, such as dimethylpolysiloxanes terminated with trimethylsiloxy groups and liquids at room temperature and high-boiling hydrocarbons such as paraffin oil, and additives such as pigments, dyes, fragrances, killers Fungicides, antioxidants, agents for affecting electrical properties, eg conductive carbon black, flame retardants, light stabilizers and agents for extending film formation time, eg with SiC-bonded mercaptoalkyl groups Silanes, cell formers (zellenerzeugende Mittel) such as azodicarbonamide, heat stabilizers and thixotropic agents such as phosphate esters and organic solvents such as alkyl aromatics.

  When using other substances (G) in order to produce a crosslinkable substance according to the invention, an amount of preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the crosslinkable substance is important. .

  The components used in the process according to the invention are commercially available products or can be prepared by conventional methods in the chemical industry.

  The components used in the process according to the invention may each be one such component or a mixture of at least two different types of this component.

  In order to prepare a crosslinkable material according to the invention, all components may be mixed with each other in any order provided that the tin catalyst (D) is 1-60% of the number of Si—OH groups, It is preferably added to the mixture containing component (A) or its reaction product only if 10-50%, particularly preferably 20-45%, is still present. This mixing is preferably carried out at a temperature of from 20 to 90 ° C., particularly preferably from 30 to 70 ° C., in particular the temperature which occurs without additional heating or cooling when the reaction components are added together at room temperature, The pressure is about 900 to 1100 hPa. However, if desired, this mixing can also be done at higher or lower pressures, such as lower pressures to prevent gas inclusion.

In one preferred embodiment of the process according to the invention, component (A), component (B), component (C), optionally filler (E) and optionally other substances (G) are mixed with one another. To the premix and then catalyst (D) and optionally stabilizer (F) are added, provided that tin catalyst (D) is still present in 1-60% of the number of Si-OH groups. Sometimes added for the first time to the premix.

In a particularly preferred embodiment of the process according to the invention, in the order of component (A), component (C), component (B), optionally filler (E) and optionally other substances (G). Mix with each other to form a premix, then add catalyst (D) and optionally stabilizer (F), except that tin catalyst (D) is still 1-60% of the number of Si-OH groups. It shall be added to the premix only when present.

  The production of the crosslinkable material according to the invention and its storage must be carried out under essentially anhydrous conditions, since otherwise the material can cure prematurely.

  Preferably, the process according to the invention is carried out under a protective gas atmosphere, particularly preferably under a nitrogen atmosphere.

  The material obtained according to the invention can be used for all purposes, for this purpose a storable material that crosslinks to an elastomer at room temperature upon entry of water under the interruption of water. Can be used.

  Thus, the material obtained according to the present invention is notably due to similar voids of seams and, for example, internal diameters of 10-40 mm, including, for example, vertically extending seams of buildings, land vehicles, ships and aircraft. Protective coatings, including protective coatings, for example in window structures or in the manufacture of water tanks or display cases, and for example for surfaces exposed to the constant action of sweet water or seawater, or Suitable as an adhesive or packing material for the production of rubber elastic moldings and for the insulation of electrical or electronic devices. Similarly, such materials may be used within the industrial scope, for example, for sealing casings, controllers, device parts and engine parts, casting components, or as protective coatings.

  In the examples described below, all viscosity descriptions are for a temperature of 25 ° C. Unless otherwise stated, the following examples are examples of ambient atmosphere, i.e., pressure of 1000 hPa and room temperature, i.e., about 23 ° C, or temperature that occurs without additional heating or cooling when the reaction components are added together at room temperature, and about Performed at 50% relative air humidity. Furthermore, all parts and percentages are by weight unless otherwise indicated.

Example 1
In a planetary mixer equipped with a vacuum part, the amount of α, ω-dihydroxypolydimethylsiloxane described in Table 1 was charged under water shut-off, and the aminosilane and the cross-linking agent were homogenized in the amounts described. Next, the filler is mixed into the mixture and the premix thus obtained is homogenized again. Secondly, when 47% of the originally present Si-OH groups are still present, tin catalyst which is a reaction product of octylphosphonic acid and dibutyltin acetate and tetraethylsilicate (Wacker-Chemie GmbH, Germany) (Available under the trade name "Katalysator 41") in the premix. After homogenization in vacuum, the formulation thus obtained is filled in a moisture-tight compact and cross-linked after the storage time described in Table 2. For this purpose, the formulation thus obtained is applied on a PE film in a 2 mm thick layer and allowed to stand at 23 ° C. and 50% relative air humidity. If the material is fully vulcanized after 24 hours, the vulcanization is evaluated as good.

  The evaluation of the vulcanization behavior is described in Table 2.

Comparative Example 1 (V1)
The method described in Example 1 is repeated, but the catalyst addition is carried out at a concentration of 69% of the initial Si—OH concentration.

  The results for the vulcanization behavior are listed in Table 2.

Example 2
The method described in Example 1 is repeated, but using the materials and amounts used in Table 1, and unlike Example 1, the addition of the catalyst was performed at a concentration of 48% of the initial Si—OH concentration. At the time of.

  The results for the vulcanization behavior are listed in Table 2.

Example 3
The method described in Example 1 is repeated, however, using the materials and amounts used in Table 1, unlike Example 1, the addition of the catalyst was performed at a concentration of 55% of the initial Si—OH concentration. At the time of.

  The results for the vulcanization behavior are listed in Table 2.

Example 4
The method described in Example 1 is repeated, but using the materials and amounts used in Table 1, unlike Example 1, the addition of the catalyst was performed at a concentration of 42% of the initial Si—OH concentration. At the time of.

  The results for the vulcanization behavior are listed in Table 2.

Example 5
The method described in Example 1 is repeated, but using the materials and amounts used in Table 1, unlike Example 1, the addition of the catalyst was performed at a concentration of 44% of the initial Si—OH concentration. At the time of.

  The results for the vulcanization behavior are listed in Table 2.

Claims (6)

In the process for producing an organopolysiloxane material that is crosslinkable to an elastomer,
(A) an organopolysiloxane having at least two hydroxyl groups;
(B) Formula RSi (OR ¹ ) ₃ (I),
[Wherein R represents a methyl group or a vinyl group, and R ¹ may be the same or different, and represents a methyl group or an ethyl group] and / or a partially hydrolyzed product thereof, The silane of (I) and / or its partial hydrolyzate is to be used in an amount of at least 0.7 parts by weight with respect to 100 parts by weight of component (A),
(C) An organosilicon compound having at least one group having basic nitrogen bonded to silicon through carbon is mixed with each other at a temperature of 20 to 90 ° C. and a pressure of the ambient atmosphere to be converted into a premix, A method for producing an elastomer-crosslinkable organopolysiloxane material, comprising adding a tin catalyst (D) when 1 to 60% of the number of SiOH groups in (A) is still present. Component (A) has the formula HO— [R ² ₂ SiO] _m —H (II)
In this case, R ² may be the same or different and represents an alkyl group having 1 to 6 carbon atoms, and m represents an organopolysiloxane (A) of 100 to 100 at 25 ° C. The method of claim 1, which is selected to have a viscosity of 1,000,000 mPas.   The method according to claim 1 or 2, wherein component (C) is an aminosilane selected from γ-aminopropyltrimethoxysilane, aminomethyltriethoxysilane, and N-aminoethylaminopropyltrimethoxysilane. Component (A), Component (B), Component (C) and Filler (E) are mixed with each other at a temperature of 20 to 90 ° C. and ambient atmospheric pressure to form a premix, and the SiOH group of component (A) sometimes to 1-60% is still present number, adding a tin catalyst (D), method according to any one of claims 1 to 3. Component (A), Component (C), Component (B) and Filler (E) were mixed together at a temperature of 20-90 ° C. and ambient atmospheric pressure to form a premix, and SiOH of component (A) sometimes to 1-60% is still present in the number of groups, the addition of a tin catalyst (D), method according to any one of claims 1 to 3. 6. The process as claimed in claim 1, wherein the tin catalyst (D) is added only when 10 to 50% of the number of SiOH groups of component (A) is still present.